Dental wax eliminator



July 21, 1931. G. w. HARRIS '1,815,960

DENTAL WAX ELI-MINATOR Filed sept. .1o. 1928 2 sheetssneag 1 2139.1 Si J6 )f 45 o o o o o o Q v odl /4 /Z y /F QMizryysf July 2 1, 1931. G. w. HARRIS 1,815,050

DENTAL WAX ELIMINATOR Filed Sept. lO. 1928 2 Sheets-Sheet 2 Patented July 21, 1931 y JNT vFFCE fGTORGJE Vl'. HARRIS, OF FERGUS FALLS, M'NNESGTA DENTAL WAX EIlMINATOR Application filed September l0, 1928. Serial le. 364,968.

My invention has for its object the provision' of an extremely simple and highly ci icient dental wax eliminator and to this end, it consists of thenovel devices and combina- .tions lof devices hereinafter described and deiined in the claims.

ln the accompanying drawings, which illustrate the invention, like characters indicate'likeparts throughout the several views.

.10 Referring'to the drawings:

Fig. lis a view ofthe improved denti l wax eliminator principally in central vertical section; and l Fig. -2 is a wiring diagram.

l5 The numeral 3 indicates an o-pen top annuliar oven removably mounted in a casing comprising concentric inner and outer shells 4 vand 5, respectively. rfliese shells 4 and 5 are radially spaced to leave an air insulating compartment G therebetween. rlhis com partment 6 at its top is closed by a lixed cover member 7 on which is formed7 directly over theshell 4 an upstanding annular bead 8 tor `a purpose 'that will presently appear. he oven 3 is concentrically positioned in the inner shell 4 and radiallyspaced therefrom to form acompartment 9 for aheating element. The

:top ot the oven 3 is below the top of the shell 4 and the compartment 9 is closed by a reycessed annular ixed cover member 10.

lt is important to note that the oven is loose from the inner cover' member 10 so thatit may be removed from the casings 4 and 5 through the bottom thereof as will presently appear.

The shell 5 extends materially below the shell 4 andis shaped to form a circumferenvtially expanded supporting' base 11 having a multiplicity of air holes 12. lThe bottom of thecasing 4 and 5 includes upper and lower bottom .plates 13 and 14, respectively, spaced vthe former above the latter to afford a compartment therebetween which .is filled with mineral wool 15 orother.insulatinginaterial The upper bottom plate 13 bears against the lower end ofthe shell 4 and the bottom member ofthe oven 3 and closes the open ,lower ends of thecoinpartments and 9.

@meatballs-ariete@trieste directly .011

the insulating body 15 and is supported therefrom. The lower bottom plate 14 bears against the lower end of the shell 5 and is held in place by a split ring 16 removably seated in an internal channel 17 in the base 11.

A cover 18 for the oven 3 is hinged at 19 to the cover member 7 and has secured to its under side a sheet of insulating material 2O which loosely rests directly on the bead 8. Resting on the bottom of the oven 3 is a thick 69 body of plaster of Paris on which is laid a base .member in the form of a metal grill 22. ldithin the compartment 9 is a heating element 23 and the lead wires therefore are indicated by the numerals 24 and 25. Interposed in the lead wire 25 is a switch comprising a relatively fixed contact member 26, a cooperating relatively movable contact member 2?, a latch 28 and a thermally influenced element 29. 7

The contact member 26, as shown, is in the form or a screw-threaded headed bolt which loosely extends horizontally through a passageway in the upper end portion of an L-shaped bracket 30. This contact member 26 is riO'idly but adjustably held against endwise movement in the bracket 30 by a pair of opposing nuts 31. Said contact member 2G is insulated from the bracket 30 and one section of the wire 25 is attached thereto and 80 theother section of said wire is grounded at 32 to said bracket.

rlhe bracket 30 at its horizontal portion is supported on a short pedestal 33 on the cover 18 at the center thereof and is rigidly secured thereto by a screw 34. Said pedestal 33 is of porcelain or other suitable insulating material which insulate the bracket 30 from the cover 18 and the screw 34 is insulated from said cover, as shown.

The movable contact member 27 vis in the forni of a lever having approximately the same shape as the bracket 30, with its lower horizontal portion,overlyingthe lower hori- Q5 Zontal portion of said bracket, and pivoted at 34 to bearing lugs on the upright portion of the bracket 30. The contact member 2.7 has a yielding terminal 35 lwhichdirectly ges the head of the dppntact meme en ber 2G and compensates tor any variation between said contact members 2G and 2T and always insures a goed contact therebetween.

leal spring 36 is provided for moving the contact member 2T to inoperative or open position in whic1 its terminal 35 is out of engagement with the contact member 2T to break the circuit to the heating element 23. @ne end oit the spring is anchored to the upright member oi the bracket SO and its other or `tree end bears on trie horizontal arm et the contact member 2.7 close to theelbow of said member and is under strain to open the same.

rllhe latch 28 is provided :for holding the contact member 2i' in an operative position against the tension ot the spring 3G and is in the form or an upright member intermediately pivoter at Si' to the outer end ot the lower` member oit the bracket On the lower end of the latch 28 is a weight 38 which normally holds said laten in an operative position. Formed on the Contact member 27 is a stop lug 39 which whe' said contact member 2.7 is closed rests on the upper end of the latch 28 and holds the contact member Q7 closed.

The thermally influenced element 29 may be of any well known type and, as shown, is of U-shap-ed toi-mation. The body et this thermally inuenced element 29 extends into a pocket 40 in the cover 18 and one of its arms extends laterally over the top ot the cover i8 ano is rigidl secured thereto by screws. T he other or tree arm ot the element 29 extends above the top oi the cover 18 and has mounted therein an adjusting screw 4l which impinges against the lower weighted end ot the latch Q8. rlhis thermally innuenceo element 29 is arranged to move in the plane ot the movement oi' the latch 28 and a piece oit the mica is interposed between the latch 28 and screw 4l and secured to said latch to insulate the thermally inline; ed element 29 from the latch 2S. The pocket 40 wliich extends into the oven 3 is Vspaced from the walls ot' said oven so that it is entirely surrounded by heat. Said pocket 40 is lined vith an insulating material. 43 which protects the element 29 trom the intense heat in 'the oven.

The arrangement ot the thermally in'tluonced element 2S) in respect to the latch Q8 is such that when said element is expanded by heat, it moves said latch from under the stop lug 39 and thereby releases the movable contact member .27 to the compressed spring 33 which moves said element into an inoperative position and thereby carries its terminal ont ot contact with the Contact member 26. A linger piece in the term et a stem is attached to the upright portion er" the contact member 2i' and by the use of which said member may be reset. The entire switch is encased in a. housing 45 secured to the cover heat.

To eliminate the wax pattern 48 from the investment 4T, said mold is placed in the oven 3 and the cover 1S closed. The movable contact member 27 is then closed by means of the linger piece 44 to complete the electric circuit 44 for the heating element 29. In closing the contact member 27, its yielding terminal 35 engages the iixed contact member 2G and is slightly compressed thereby. During the losing movement oit the contact member 27 the stop lugl 39 is moved slightly above the latch Q8 which allows said latch to swing by gravity under the stop lug 3S and into contact with the adjusting screw 4l. It may be here stated that when the Contact member 27 is open, the latch Q8 is held in an oblique position by the stop lug 39.

After the cont-act member 2.7 has been mover` suliiciently to permit the latch QS to move under its stop lug Q8, the linger piece 44 is released and the yielding terminal and spring 86 will move the contact member 2T slightly downward until stopped by he engagement of the stop lug 39 with the latch 2S. When the Contact member 2'! is closed, the circuit for the heating element L3 is closed through the contact member QG, terminal 35, contact member QT and bracket 30. As the heat in the oven 3 increases, the tree arm ol the thermally influenced element 2S) carries the adjusting screw 41 toward the latch 28 and thereby gradually moves the same from under the stop lug 39 and allows the Contact member Q7 to be opened by the spring 36 to break the circuit to the heating element 23.

By adjusting the screw 4l the period oi time in which the switch is closed may be varied7 at will, so that any desired amount o't heat maybe supplied to the oven 3 tor driving oil' the moisture contents i n the investment 47 and melt t ie wax pattern 4S so that the same will flow through the sprue 50 into the recess 49 and on to the grid 22. Steam produced in the oven 3 during the elimination ot the wax pattern 48 will escape therefrom under the loosea cover 1S. By the use ot theI above described thermally ini'iuenced element 29, the period ot time in which the heat is applied to the oven 3 entirely automatic so that after the operator places the mold in the oven closes the cover 18 and switch h@ need not give the same any further consideration whatsoever.

All danger is eliminated by the use of this element 29, of not supplying sutlicient heat to the oven 3 to drive oil the moisture contents in the investment 47 and eliminate the wax pattern 48 or in creating too much heat with a result that the investment 47 and the wax pattern 48 are damaged to such an extent that they can not be used with the result that the work of producing another pattern will have to be repeated.

After the switch has been opened under the action of the thermally influenced element 29, the mold may be left in the oven 3 to gradually cool therewith. In case it is desirable to again use the oven 3, the cover 18 may be opened to carry the thermally influenced element 29 away trom the heat in the oven 3 so that the same will very quickly assume normal position and permit the switch to be again closed.

n case it is necessary to remove the heating element 23, it may be very easily and quickly done by releasing the split ring 16 and removing the bottoni plates 13 and 14, insulation 15, oven 3 and heating element 23.

What I claim is:

1. The combination with an open top oven, and a displaoeable cover normally closing the same and having an external pocket extending into the oven and movable therefrom with the opening of the cover, ot' an electric circuit for the heating element including a switch carried by the cover, and means including a thermally influenced `element in the pocket for opening the switch.

2. The structure delined in claim 1 in which the switch is arranged to be manually closed.

3. The combination with an open top oven, and a displaceable cover normally closing the same and having an external pocket eX- tending into the oven and movable therefrom with the opening ot the cover, ot an electric circuit lor the heating element including a switch carried by the cover, said switch being under strain to open, a trip normally holding the switch closed, and a. thermally inluenced element in the pocket for operating the trip to permit the switch to open.

4. The combination with an open top oven, and a displaceable cover normally closing the same and having an external pocket eX- tending into the oven and movable therefrom with the opening .of the cover, ot an electric circuit for the heating element including a switch carried by the cover, said switch being under strain to open, a gravity positioned trip, a thermally influenced element in the pocket for operating the trip to permit the switch to open.

5. The structure delined in claim 4 in which the switch is arranged to be manually GEORGE `W. HARRIS. 

